Changes on chemical composition of cocoa beans due to combined convection and infrared radiation on a rotary dryer

Abstract

Cocoa production around the world is characterized by a lack of technical facilities for post-harvest activities, and therefore a good quality of beans is hard to achieve. This situation can be changed by using technological solutions, particularly when they are adapted to specific needs of cocoa producers. Mechanical dryers used in intensive cocoa production exceed the smallholders’ requirements and because of the large amounts of energy they consume, there is a substantial economic and environmental impact. At this regard, improvement of alternative mechanical drying techniques requires a careful assessment of their impact on cocoa quality. Then this work looks forward to evaluating the chemical changes on cocoa beans due to the combined use of convection and radiation in a rotary dryer. It highlights not only the experimental set ups but also the analysis methods involved in the chemical characterization. High Performance Liquid Chromatography (HPLC) and Spectrophotometry are the chemical analysis tools used in this study. On one hand, total polyphenols content is determined by means of a spectrophotometric method based on the use of the Folin & Ciocalteu’s reagent and a mix of hexane-isopropanol at pH = 9 as extraction solution. Similarly, in order to identify the impact of the combined drying strategy on the concentration not only of Polyphenols (Catechin and Epicathechin) but also of Methylxanthines (Caffeine and Theobromine) a chemical identification and quantification of these compounds are done using HPLC with UV detector and a C-18 column, using water, methanol and acetic acid as mobile phase.